Soil Application of Zinc Fertilizer Increases Maize Yield by Enhancing the Kernel Number and Kernel Weight of Inferior Grains.

Dun-Yi Liu,Chun-Qin Zou,Yu-Min Liu,Xin-Ping Chen,Wei Zhang

doi:10.3389/fpls.2020.00188

Dun-Yi Liu, Chun-Qin Zou + Show 3 more

Open Access

https://doi.org/10.3389/fpls.2020.00188

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Abstract

Improving the development of inferior grains is important for increasing maize yield under high-density conditions. However, the effect of micronutrients, especially zinc (Zn), on the development of inferior grains and maize yield under field conditions has not been evaluated to date. A field experiment with six Zn application rates (0, 2.3, 5.7, 11.4, 22.7, and 34.1 kg/ha) was conducted to investigate the effects of soil application of Zn fertilizer on the development of inferior grains. Pollen viability was measured at the tasseling stage. The maize spike was divided into apical (inferior grain), middle, and basal sections for further measurement at harvest. Results showed that soil application of Zn fertilizer increased maize yield by 4.2–16.7% due to increased kernel number and weight in the apical, but not in the middle and basal sections. Zn application also significantly increased pollen viability at the tasseling stage. The critical Zn concentrations in shoots at the tasseling stage for obtaining high pollen viability and high kernel numbers of inferior grains were 31.2 and 35.6 mg/kg, respectively. Zn application also increased the 1,000-kernel weight of inferior grain due to high biomass accumulation. Furthermore, the grain Zn concentration of inferior grain with Zn application increased by 24.3–74.9% compared with no Zn application. Thus, soil application of Zn fertilizer successfully increased grain yield of maize by improving pollen viability, kernel number, and kernel weight of inferior grains (apical section), also contributing to grain Zn biofortification.

Highlights

As a common staple food, fuel, and feed, maize (Zea mays L.) yields have continued to increase (Duvick, 2005; Nuss and Tanumihardjo, 2010)
Excessively high density can lead to a decline in maize yield (Boomsma et al, 2009), mainly because the kernel numbers per spike often decline with increasing plant density (Sangoi, 2001), especially in the apical section (Chen et al, 2013)
This study aimed to quantify the effects of Zn fertilizer on pollen viability, kernel number, and grain weight in different sections of the maize spike, with focus on inferior grains, and explored how Zn application improved the development of inferior grains and contributed to yield increase in maize

Summary

Introduction

As a common staple food, fuel, and feed, maize (Zea mays L.) yields have continued to increase (Duvick, 2005; Nuss and Tanumihardjo, 2010). A sufficient kernel number per spike and high kernel weight are important for guaranteeing a high maize yield at certain densities (Borrás and Otegui, 2001). One physiological basis for the improvement of modern maize hybrids is an increase in kernel number per unit area, which accounts for most of the variation in maize yield (Duvick, 1997). Increasing plant density in the newest hybrids is the main strategy for improving yield in maize (Ma et al, 2014; Di Matteo et al, 2016). Excessively high density can lead to a decline in maize yield (Boomsma et al, 2009), mainly because the kernel numbers per spike often decline with increasing plant density (Sangoi, 2001), especially in the apical section (Chen et al, 2013)

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